Semiconductor fabrication introduces imperfections such as dangling bonds and charge traps on channel surfaces and interfaces. Addressing these defects becomes challenging with miniaturized structures and low-dimensional materials, because high-energy treatments may cause secondary damage. Ionized hydrogen in the liquid phase neutralizes negatively charged defects through chemical reactions. The bis(trifluoromethanesulfonyl)imide (H-TFSI) solution, effective in mitigating defects in MoS2, lacks verification of its mechanism and impact on device performance. Treating monolayer MoS2 FET with H-TFSI induces simultaneous enhancement and degradation, complicating our understanding of the specific reactions. This study employed monolayer and multilayer MoS2 devices to distinguish the surface and gate dielectric interface influence. In addition to the DC measurements for device performance analysis, low-frequency noise characteristics were examined to provide a more detailed depiction of the interface traps. Treating multilayer MoS2 with H-TFSI results in more than a 2-fold increase in carrier mobility, and applying a negative gate voltage to further enhance the hydrogen ion reaction leads to a mobility increase exceeding 3-fold, reaching a high value of 128.3 cm2/V s compared to the baseline device. The interface trap density decreased, and the threshold voltage shifted positively. This signifies that the hydrogen ions from H-TFSI validated their remarkable healing effects on the surface and interface defects in MoS2 devices by demonstrating their superior performance in passivating interface traps and neutralizing material defects.
Keywords: H-TFSI; MoS2; defect neutralization; interface characterization; proton injection; sulfur vacancy.